The top 18 nutrition myths of 2018

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You’d think that, as time goes on, there would be fewer nutrition myths for us to tackle.

Unfortunately, the internet is rife with misinformation, and it can be really difficult to tell what’s evidence-based without reading the original research yourself. Myths that were previously passed through word-of-mouth in gyms and health clubs now spread like wildfire through social media, blogs, and even established media. Between a 24-hour news cycle, studies that are both long and difficult to read, and journalists scrambling for the latest viral hit, information often gets published without being verified.

As an educational organization that looks only at the evidence, we’ve taken the time to identify the top 18 nutrition myths that just won’t die. At the end of each section you’ll find a link to a page that further explores the topic and provides references.

Myth 1: Carbs are bad for you

For decades, fat was the enemy; today, there’s a new scapegoat: carbs. And generalizing about carbs and insulin seems to get more popular by the year. In fact, many people mistakenly believe that the popular glycemic index (along with the less well-known insulin index) rank foods by how dangerous they are. Yet low-glycemic diets haven’t shown an advantage in rigorous clinical trials.[1]

Insulin has obtained a bad reputation, and its effects are widely misunderstood.

Early evidence suggested that carbs could cause your body to be less sensitive to insulin — the hormone that helps regulate your blood sugar levels. This can be true in diabetics and in insulin-resistant people overeating carbs, but not in healthy people on a healthy diet. The development of insulin resistance is multifactorial; excess fat, physical inactivity, poor sleep, and genetics all play a role. This said, there is no denying that modern society makes it very easy to overeat carbs: processed carbs are often delicious and seldom very filling, despite being high in calories.

At the end of the day, trans fat is the only kind of fat that has been shown to be categorically detrimental to health — a little won’t kill you, but avoid it when you can.[3]

The Truth: If you stay in a caloric surplus, a low-fat diet won’t make you lose weight. You need some omega-3 and omega-6 fatty acids, and saturated fat won’t give you a heart attack (but too much trans fat may).

Myth 3: Protein is bad for you

Carbs and fats often take the blame for various health issues, but the third macronutrient isn’t always spared by the media. Protein has often been accused of causing bone and kidney damage.

Let’s tackle those two claims one at a time. An early study reported that protein consumption was linked to increased urinary calcium, which was thought to be coming from the bones — for that reason, protein was linked to a risk of bone loss. Later studies, however, determined that urinary calcium was a poor predictor of bone mass, and that protein actually had a protective or neutral effect on bones.[4][5]

Another early study determined that high protein diets increased glomerular filtration rate (GFR), a marker for waste filtration in the kidneys.[6] It was argued that increased GFR was a sign that undue stress was put on the kidneys, but later research has shown that kidney damage does not occur as a result of diets high in protein.[7][8]

Myth 5: Red meat is bad for you

Absolute statements are why we have so many nutrition myths. Cancer is particularly difficult to discuss in absolutes. After all, almost everything we eat has the potential to be involved in cancer development.[11] For example, antioxidants can both promote and hinder cancer growth, but the effect is usually too small to notice.

Some compounds — such as polyaromatic hydrocarbons (PAHs), found in smoked meats — have been found to damage the genome, which is the first step to potential cancer. Current evidence suggests that red meat can pose a cancer risk for people with poor diets and lifestyle choices.[12][13] But if you exercise regularly, eat your veggies, and don’t smoke, red meat’s effect on cancer isn’t something to worry too much about.

The Truth: Fears about red meat causing cancer are vastly exaggerated. Making healthy lifestyle choices (such as staying at a healthy weight, exercising, and not smoking) is more important than micromanaging your red meat intake. Still, if you plan to decrease your intake of red meat, start with the kind that has been cured, smoked, or highly processed.

Another issue is the source of all that salt. The average North American eats an incredible amount of salty processed foods[18] — which means that people who consume a lot of salt tend to consume a lot of foods that are generally unhealthy. That makes it hard to tease apart sodium’s effects from overall dietary effects. Except for individuals with salt-sensitive hypertension,[19] the evidence in support of low sodium intakes is much weaker than most people would imagine.[20] As it stands, both very high and very low intakes are associated with cardiovascular disease.[21]

The Truth: Salt reduction is important for people with salt-sensitive hypertension, and excess salt intake is associated with harm. But drastically lowering salt intake has not shown much benefit in clinical trials. Most people will benefit more from a diet of mostly unprocessed foods than they would from micromanaging their salt intake.

Myth 7: Bread is bad for you

Bread has taken a beating over the past few years (especially white bread). The bread detractors generally make two arguments against its consumption:

Bread will not inherently make you fat, but it tends to be dense in calories and therefore easy to overeat. And of course, most people will eat bread with other high-calorie foods, such as butter, peanut butter, jam, or honey. This can lead to a caloric surplus and thus to weight gain over time. Moreover, while bread can be part of a healthful diet, a bread-centric diet can crowd out more nutrient-rich foods, notably fruits and vegetables.

Also, some people choose to avoid bread entirely because of its gluten content. Gluten critics claim that any amount of gluten (a protein, ironically, not a carb) is a danger to all. While “all” is an exaggeration, it is indeed possible to suffer from non-celiac gluten sensitivity.[22][23] However, it is also possible for your wheat sensitivity[24] to be caused by other compounds, such as FODMAPS (short-chain carbohydrates known to promote intestinal distress by fermenting and producing gas).[25][26]

White bread vs. whole-wheat bread

You may have heard that eating bread is all right as long as it’s whole-wheat bread. While white bread (made from wheat flour) and whole-wheat bread provide a similar number of calories, whole-wheat bread has a lower glycemic index and insulin index, and so its consumption results in a lower insulin release. For that reason, and because of its higher fiber and micronutrient content, whole-wheat bread is claimed to be healthier than white bread.

What the media frequently fails to mention is that the actual differences between white bread and whole-wheat bread are relatively small. Yes, whole-wheat bread has a higher fiber content — but this content pales compared to that of many fruits and vegetables. You most definitely don’t have to eat whole-wheat products to get enough fiber in your diet! And yes, white bread does lose more micronutrients during processing — but those micronutrients are often reintroduced later (the bread is then called “enriched”).

The Truth: While some people are sensitive to wheat, the gluten content isn’t necessarily to blame, and other foods may also be implicated. Bread will not make you fat unless its consumption puts you in a caloric surplus. Though whole-wheat bread is claimed to be far healthier than white bread, they aren’t that different, and neither contains high levels of fiber or micronutrients.

Myth 8: HFCS is far worse than sugar

Glucose, the sugar in your blood, is your body’s preferred source of energy. Fructose, another sugar, can also be used for energy via its conversion to lactate and glucose in the liver.

Early evidence led to the belief that fructose could cause fatty-liver disease, as well as insulin resistance and obesity. By extension, high-fructose corn syrup (HFCS) is frequently said to be unhealthy, since it is high in fructose.

Myth 9: Fresh is more nutritious than frozen

Fresh produce has a natural appeal to many people. It just sounds better than “canned” or “frozen” fruits and vegetables. But just because a food is “fresh” doesn’t necessarily mean it’s more nutritious.

Fresh produce is defined as anything that is “postharvest ripened” (if it ripens during transport) or “vine-ripened” (if it is picked and sold ripe: at a farm’s fresh market or at a farmer’s roadside fruit stand, for instance).

Frozen produce is generally vine-ripened before undergoing minimal processing prior to freezing. Most vegetables and some fruits undergo blanching in hot water for a few minutes before freezing, in order to inactivate enzymes that may cause unfavorable changes in color, smell, flavor, and nutritional value.[27]

While there are some differences between fresh and frozen for select nutrients in select fruits and veggies, overall they have very similar nutritional content.[28]

The Truth: While there can be some nutrient differences between fresh and frozen produce the overall differences are small.[28] Pick whichever suits your taste, budget, and lifestyle.

Myth 10: Foods are always superior to supplements

How often have you heard the claim that whole foods are always better than supplements? It’s been repeated so often that the word “natural” has a positive connotation whereas “synthetic” or “chemical” has a negative one.

The truth, of course, isn’t so clear-cut. Some compounds are more effective in supplemental form. One example is the curcumin in turmeric. On its own, your body cannot absorb it well; but taken in liposomal form[29] or supplemented with piperine, a black pepper extract, curcumin sees its bioavailability increase dramatically.

Many supplemental vitamins have natural and synthetic forms. This makes them accessible to more people. For example, if B12 could not be synthesized, it would be prohibitively expensive as well as unsuitable to vegans.

The Truth: With regard notably to vitamins, foods are not always superior to supplements.

Myth 11: Dietary supplements are necessary

This is a favored line of thinking by supplement companies and health gurus. One argument is that intensive agriculture has led to soil depletion,[31] so that natural foods (vegetables and grains and the animals fed on them) fail to provide enough vitamins and minerals. Another argument is that foods are a mess of unknown compounds, in addition to known “poisons” such as the dreaded saturated fat, cholesterol, gluten, and FODMAPs. And to top it all, sticking to a low-carb or low-fat or high-protein diet with only foods is a daily challenge.

Fact is, multis are seldom well conceived. Due to cost and space considerations (people willing to take one pill a day may balk at taking ten), multis are often rich in micronutrients abundant in a healthy diet and poor in others you are more likely to need. You are usually better served by focusing on what you actually need — such as vitamin B12 if you are vegan or a senior, or vitamin D if you seldom see the sun.

In fact, many foods you’ll find at the supermarket are already fortified with the micronutrients you’re most likely to lack. Milk, for instance, is frequently fortified with vitamin D, whereas salt is iodized, and enough foods are fortified with folic acid that you’re as likely to get too much as not enough. In that light, many of our foods are already fortified with vitamins and minerals; it is therefore tempting to take the next step and live on meal replacements, with all the necessary nutrients added in and none of the aforementioned “poisons”.

That could work — if we actually knew “all the necessary” nutrients. We learn a little more each day, but there’s still much we don’t understand about food components and their interactions with different systems in our bodies (and with different people). So, until we reach a perfect understanding of the human body and its nutritional needs, you’re safer eating a varied diet of little-processed foods than ingesting the same meal replacement day after day after day. And it’ll taste better.

The Truth: Supplements have their use. You can benefit from supplementing specific vitamins or minerals, and a protein powder can make it easier to increase your daily protein intake. But supplements should complete a healthy diet — not replace it.

Myth 12: You should eat “clean”

This statement is not so much a myth as a jumble of misconceptions. First of all, people seldom agree on what “clean” actually means. For some, it means avoiding everything that isn’t “natural”. For others, it means avoiding all “risky foods” even at the cost of living on meal replacements and other supplements. One common point of clean diets is their focus on exclusion: they tell you what clean eating is by telling you what not to eat.

Veganism can be considered a prototypal clean diet, as it shuns all meat products both for ethical reasons and for better health. But although vegans and vegetarians do live longer,[33] this may be influenced by reasons unrelated to food. For instance, people who stick to a vegetarian diet are more likely to also stick to an exercise regimen, practice relaxation exercises (meditation, yoga …), and neither drink in excess nor smoke.

But animal products aren’t the only “unclean” foods for clean-diet proselytizers. You can’t simply “eat your veggies” — you need to make sure they’re organic. This is presented as self-evident, on the principle that “natural” is good whereas “synthetic” is bad; yet research has so far failed to link organic foods, plants or animal, to better health.[34] It doesn’t mean a link cannot exist, but the organic-versus-conventional debate is complex, and can change both with the foods under scrutiny and with the individuals eating them.

One misconception is that no synthetic substance can be used to grow organic crops, whereas the National List of Allowed and Prohibited Substances makes some exceptions. Another misconception is that no pesticide can be used to grow organic crops, whereas natural pesticides exist, are used to grow organic crops, and are not always better for the consumer or the environment.[35]

Pesticide residues in food are a valid concern, though it should be noted that the Pesticide Data Program (PDP) of the United States Department of Agriculture (USDA) has consistently found that the vast majority of the food on the market contained residues below the tolerable limits set by the Environmental Protection Agency (EPA). In addition, rinsing, peeling when possible, and cooking can reduce the amount of pesticide left on your food.

Is our food clean enough yet? Not quite. Some “clean eating” gurus recommend that you only eat your food raw, so as not to “denature” its nutrients. As an absolute, this rule is bunk. Raw milk can contain harmful bacteria. Raw eggs contain avidin, a protein that can bind biotin and thus lead to biotin deficiency. Cooking can reduce the nitrate content of vegetables (bad) but also their oxalate content (good). You can’t generalize.

It’s easy to see how one can push the “clean eating” obsession too far, even all the way into orthorexia. It doesn’t mean that all foods are equal, and you certainly should favor whole foods over processed foods — most of which are nutrient-poor, calorie-dense, and easy to overeat — but you shouldn’t fear that eating anything but raw organic veggies is going to drastically shorten your lifespan.

The Truth: “Clean eating” is tough to define, as gurus don’t even agree on which foods are clean and which are not. Stick to the basics. Favor whole foods (but don’t feel like any small amount of processed foods will kill you), eat organic if you want and can afford it, peel or wash all your vegetables and fruits, and avoid stressing too much about what you eat, since stress can shorten your lifespan.[36]

Myth 13: You should “detox” regularly

“Detox diets” are the ultimate manifestation of the “clean eating” obsession. Such diets commonly limit foods to plant-based juices, sometimes seasoned with a supplement. After a few days of that regimen, you’re supposed to be cleansed of …

Of what? Good question. A 2009 investigation of ten companies found they couldn’t name the “toxins” targeted by any of their fifteen products — let alone prove that their products worked. Strictly speaking, toxins are plant- or animal-based substances poisonous to humans; but for many detox gurus, “toxins” also include heavy metals … and everything synthetic: not just toxicants (man-made poisons, such as pollutants or pesticides), but also preservatives, high-fructose corn syrup, etc.

Alas, even when a substance really is noxious, a “detox diet” won’t help. Acute toxicity would likely constitute a medical emergency, whereas chronic toxicity is best addressed by a well-fed body — not one weakened by a severely hypocaloric diet. The liver, kidneys, lungs, and other organs work around the clock to remove harmful substances and excrete the waste products of metabolism; detoxes can make it harder for them to work! Detox diets are not necessarily safe, either. Every now and then a case report emerges about potential risks, such as kidney damage from green smoothies[37] or liver failure from detox teas.[38]

But if “detox diets” are more likely to harm than help, what explains their current popularity? One answer is quick weight loss. Deprive your body from carbohydrate and you can exhaust its glycogen stores in as little as 24 hours. The resulting loss of several pounds can convince you the diet had a positive effect.[39] When the diet ends and you resume your regular eating habits, however, the glycogen and associated water come rushing back in, and with them the pounds you’d shed.

The Truth: Focus on sustainable health habits, such as eating nutritious food on a daily basis. Ample protein, leafy greens, and foods chock-full of vitamins and minerals are not just tastier than anything a “detox diet” has to offer, they’re also way better for you (and your liver detoxification pathways, ironically). A detox diet might make you feel better, but that’s usually because of the increased vegetable and fruit intake, not because any form of detoxification is taking place.

Myth 14: Eat more often to boost your metabolism

It’s easy to trace this myth back to its origin. Digestion does raise your metabolism a little, so eating less food more often should keep your metabolism elevated.

In theory.

In practice, evidence shows that, given an equal amount of daily calories, the number of meals largely makes no difference in fat loss.[40] Moreover, some studies suggest that having smaller meals more often makes it harder to feel full, potentially leading to increased food intake.[41] Your metabolism can fluctuate based on the size of the meal, so fewer but larger meals means a larger spike in metabolism. Over the course of a day or week, given an equal amount of calories, the number of meals doesn’t seem to matter — it all evens out.

The Truth: Digestion does slightly increase your metabolic rate, but meal frequency has less effect than the total caloric content of the food consumed.

Myth 15: You need to eat breakfast

“Breakfast is the most important meal of the day” is something we have all heard before from parents, health bloggers, doctors, and ad campaigns. But the health advantage of consuming a regular breakfast has been overhyped.

People who are #TeamBreakfast have pointed to observational studies showing a higher BMI in breakfast skippers.[42] However, clinical trials have pointed to personal preference being a critical factor. Some people will subconsciously compensate for all the calories they skipped at breakfast, while others won’t feel cravings of the same magnitude. In one trial, women who didn’t habitually eat breakfast were made to consume it; they gained nearly 2 pounds over a 4-week period.[43] Individual responses do vary, so don’t try to force yourself into an eating pattern that doesn’t sit well with you or that you can’t sustain — it may end up backfiring.

Another popular claim is that skipping breakfast can crash your metabolism. But studies in both lean and overweight individuals have shown that skipping breakfast does not inherently slow your resting metabolic rate (RMR).[44][45]

One area where the “don’t skip breakfast” mantra may hold true is in people with impaired glucose regulation. These individuals may want to play it safe and avoid skipping breakfast in order to achieve better day-to-day glucose management.[45]

The Truth: You don’t need to eat breakfast to be healthy or lose weight. You should base your breakfast consumption on your preferences and personal goals. Feel free to experiment to see if you want to make skipping breakfast a habit.

Myth 16: To lose fat, don’t eat before bed

Some studies show a fat-loss advantage in early eaters, others in late eaters. Overall, early eaters seem to have a slight advantage — nothing impressive. Trials, however, imperfectly reflect real life. In real life, there are two main reasons why eating at night might hinder fat loss, and both are linked to an increase in your daily caloric intake.

The first reason is the simplest: if, instead of going directly to bed, we first indulge in a snack, then the calories from that snack are calories we might have done without.

The second reason is that, when we get tired, we tend to eat to keep going, with a predilection for snack foods or tasty treats. So if we stay awake at night — especially to work or study, but even just to watch TV — we’re more likely to eat, not out of hunger, but to help fight sleepiness.

The Truth: Eating late won’t make you fat, unless it drives you to eat more. It can also be harder to resist tasty, high-calorie snacks after a long day.

Myth 17: To lose fat, do your cardio on an empty stomach

Let’s get one thing out of the way. If you exercise near maximal capacity (sprints, HIIT, heavy lifting …), eat first, or you’re more likely to underperform. Most people who choose to work out in a fasted state, however, opt for some more moderate form of “cardio” (aerobic exercise), such as jogging.

During cardio, performance and energy expenditure in the fasted state are about the same as in fed state. In the fasted state, you’ll burn more body fat, but that won’t make it easier for you to use body fat as fuel during the rest of the day (when you’re fed). You’ll also burn a tiny bit more muscle, but you’ll grow it back faster afterward, too — it seems to balance out (as long as you get enough protein). Finally, cardio suppresses appetite less in the fasted state than in the fed state, but that doesn’t translate into a significant difference in daily caloric intake.

The Truth: There’s very little difference between cardio in the fed or fasted state, be it with regard to fat loss, muscle preservation, daily caloric intake, or metabolic rate. What really matters, then, is you. Some people feel lighter and energized when they do cardio on an empty stomach, while others feel light-headed and sluggish. Fed or fasted state: pick whichever makes you feel better.

Myth 18: You need protein right after your workout

When you exercise, you damage your muscles, which your body then needs to repair, often making them more resilient (bigger) in the process. The raw material for this repair is the protein you ingest, yet the existence of a post-workout “anabolic window” for this ingestion remains a contentious topic in the literature.[46][47]

“You need protein right after your workout” may not be a myth so much as an exaggeration. Consuming 20–40 g of protein within the two hours following your workout may be ideal, but it isn’t necessary. What matters most is your daily protein intake. To maximize muscle repairs, aim for 1.4–2.2 g of protein per kilogram of bodyweight per day (0.64–1.00 g/lb/day).

The Truth: You don’t need protein immediately after your workout, but you might benefit from 20–40 g within within the next couple of hours (and before bed). What matters most, however, is how much protein you get over the course of the day.

Misinformation in the Mainstream

You’ve likely heard all 18 of these myths repeated at one time or another — by a friend, on a blog, or somewhere in the media. Misinformation is rampant, difficult to identify, and unfortunately spreads much faster than facts.

And really, this is just the tip of the iceberg. You’ll see often see sensationalist headlines based on a study with unsurprising results. In mid-2017, for instance, the media went into a frenzy of similar headlines claiming that a study showed that coconut oil was “bad” for you. Of course, when we analyzed the study, we found that coconut oil, like most other natural foods, has both benefits and downsides. Even the recent major 8 million dollar study by Stanford that studied low-fat vs low-carb was misrepresented all over the media.

It’s why we have an entire team poring over the research. And not just one or two studies, either — but the entire body of evidence.

Evidence-Based Information

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